2151. Producer gas is produced by_____________________?
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A. passing steam over incandescent coke

B. passing air and a large amount of steam over waste coal at about 65C

C. carbonisation of coal

D. same way as the natural gas

E. partial combustion of coal, coke, anthracite coal or charcoal in a mixed air steam blast
2152. A gas turbine used in air craft should have______________________?
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A. high h.p. and low weight

B. high speed and high h.p.

C. small frontal area and high h.p.

D. all of the above

E. low weight and small frontal area
2153. Reheating in multistage expansion gas turbine results in____________________?
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A. decrease of heat loss in exhaust

B. none of the above

C. maximum work output

D. high thermal efficiency

E. reduction in compressor work

2154. High air-fuel ratio is used in gas turbines______________________?
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A. to save fuel

B. to reduce the exit temperature

C. to increase the efficiency

D. to increase the output

E. none of the above

2155. The efficiency and work ratio of a gas turbine plant can be increased by _____________________?
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A. all of the above

B. using mulit-stage compressor with mfercooler

C. adding heat exchanger

D. reheating the air after partial expansion in the turbine

E. injecting water in/around combustion chamber

2156. Ram compression in turbojet involves____________________?
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A. lost work

B. increasing speed of incoming air

C. compression of inlet air

D. leakage losses

E. reduction of speed of incoming air and conversion of part of it into pressure energy
2157. A compressor at high altitude will draw________________?
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A. less power

B. none of the above

C. more/less power depending on other factors

D. same power

E. more power

2158. For slow-speed large capacity compressor, following type of valve will be best suited________________?
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A. none of the above

B. disc or feather type

C. poppet valve

D. mechanical valve of the corliss, sleeve, rotary or semirotary type

E. any of the above

2159. Pick up the correct statement ?
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A. large gas turbines use radial inflow turbines

B. gas turbines have their blades similar to steam turbine

C. gas .turbines blade will appear as impulse section at the hub and as a reaction section at tip

D. gas turbines use both air and liquid cooling

E. all of the above are correct.

2161. Free air is the air at________________?
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A. 25C, 1 kg/cm2 and relative humidity of 50%.

B. 20C and 1 kg/cm2 and relative humidity of 36%

C. 15C and 1 kg/cm2

D. atmospheric conditions at any specific location

E. 0C and standard atmospheric conditions

2162. Pick up the false statement ?
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A. gas turbine can be easily started and stopped and thus is best suited for peaking demands

B. exhaust losses in gas turbine are high due to large mass flow rate

C. gas turbine is a self-starting unit

D. gas turbine does not require huge quantity of water like steam plant

E. overall efficiency of gas turbine plant is lower than that of a reciprocating engine

2163. The clearance volume of the air compressor is kept minimum because____________________?
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A. none of the above

B. it permits isothermal compression

C. it greatly affects volumetric efficiency

D. it allows maximum compression to be achieved

E. it results in minimum work

2165. The blades of gas turbine are made of_________________?
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A. high alloy seel

B. mild steel

C. carbon steel

D. high nicket alloy (neimonic)

E. stainless steel

2167. Reheating in gas turbine results in___________________?
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A. increase of work ratio

B. decrease of thermal efficiency

C. decrease of work ratio

D. both A. and B. above

E. both B. and C. above

2168. The material commonly used for air craft gas turbine is__________________?
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A. stainless steel

B. titanium

C. Timken, Haste and Inconel allpys

D. duralumin

E. high alloy steel

2169. In jet engines the compression ratio__________________?
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A. varies as square root of the speed

B. Varies linearly to the speed

C. varies as square of the speed

D. varies as cube of the speed

E. is constant irrespective of variation in speed

2171. The degree of reaction of an axial flow turbine is the ratio of isentropic temperature drop in a blade row to the_____________________?
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A. total temperature drop

B. total adiabaitc temperature drop

C. adiabatic temperature drop in the stage

D. difference of maximum and minimum temperature in the cycle

E. total temperature drop in the stage
2172. Rotary compressor is best suited for_____________________?
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A. large quantity of air at high pressure

B. any one of the above

C. small quantity of air at low pressure

D. large quantity of air at low pressure

E. small quantity of air at high pressure
2174. Gas turbine blades are given a rake___________________?
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A. equal to zero

B. in the direction of motion of blades

C. opposite to the direction of motion of blades

D. depending on the velocity

E. none of the above

2175. Adiabatic compression is one in which___________________?
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A. work done is maximum

B. entropy decreases

C. no heat leaves or enters the compressor cylinder during cornpression

D. temperature rise follows a linear relationship

E. temperature during compression remains constant

2176. The- most efficient method of compressing air is to compress it_________________?
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A. isochronically

B. adiabatically

C. as per law pV

D. isothermally

E. isentropically

2177. The overall isothermal eiffciency of compressor is defined as the ratio of_______________?
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A. isothermal work to ideal work

B. work to compress air isothermally to work for actual compression

C. power to drive compressor to isothermal h.p.

D. isothermal h.p. to the BHP of motor

E. isothermal h.p. to adiabatic h.p.

2178. Work ratio of a gas turbine plant is ratio of______________________?
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A. net work output and heat supplied

B. actual/heat drop and isentropic heat drop

C. work done by turbine and net work output

D. work done by turbine and heat supplied

E. net work output and work done by turbine
2179. Pick up the correct statement?
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A. thrust in turbo-jet is produced by nozzle exit gases

B. gas turbine uses same working fluid over and over again

C. closed cycle gas turbine is an I.C engine

D. ideal efficiency of closed cycle gas turbine plant is more than carnot cycle efficiency

E. air-fuel ratio in a gas turbine is 100 : 1

2180. The ratio of isentropic work to Euler work is known as_____________________?
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A. work coefficient

B. compressor efficiency

C. pressure coefficient

D. polytropic reaction

E. slip factor

2181. The compressor performance at higher altitude compared to sea level will be _______________?
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A. same

B. none of the above

C. dependent on other factors

D. lower

E. higher

2182. The thermal efficiency of a simple gas turbine for a given turbine inlet temperature with increase in pressure ratio_____________________?
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A. increases

B. decreases

C. remains same

D. first decreases and then increases

E. first increases and then decreases

2183. In the axial flow gas turbine, the work ratio is the ratio of____________________?
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A. compressor work and turbine work

B. actual compressor work and theoretical comprssor work

C. actual total head tempeature drop to the isentrpic total head drop from total head inlet to static head outlet

D. output and input

E. none of the above

2184. Reciprocating air compressor is best suited for___________________?
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A. large quantity of air at low pressure

B. small quantity of air at low pressure

C. small quantity of air at high pressure

D. any one of the above

E. large quantity of air at high pressure
2185. Separators in compressor installations are located_____________________?
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A. after receiver

B. before suction

C. before intercooler

D. after intercooler

E. between after-cooler and air receiver
2186. The indicated work per unit mass of air delivered is___________________?
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A. inversely proportional to clearance volume

B. directly proportional to clearance volume

C. not affected by clearance volume

D. greatly affected by clearance volume

2187. The ratio of work doen per cycle to the swept volume in case of compressor is called ______________?
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A. mean effective pressure

B. compressor effectiveness

C. compression index

D. compressor efficiency

E. compression ratio

2188. Maximum work is done in compressing air when the compression is_________________?
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A. adiabatic

B. any one of the above

C. isothermal

D. polytropic

E. none of the above

2189. The criterion of the thermodynamic efficiency for rotary compressor is_________________?
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A. polytropic compression

B. isentropic compression

C. isothermal compression

D. any one of the above

E. none of the above

2190. The following is true for an open cycle gas turbine having exhaust heat exchanger. Atmospheric air before entering the compressor is____________________?
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A. bled gas from turbine is heated and readmitted for complete expansion

B. compressed air before entering the combustion chamber is heated

C. exhaust gases drive the compressor

D. heated

E. part of exhaust gases are heated and mixed up with atmospheric air to utilise exhaust heat

2191. The fuel consumption in gas turbines is accounted for by___________________?
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A. higher heating value

B. heating value

C. highest calorific value

D. low.er heating value

E. higher calorific value

2192. What will be the volume of air at 327C if its volume at 27C is 1.5 m3/mt ?
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A. 3 m3/mt

B. 18 m3/mt

C. 0.75 m3/mt

D. 1.5 m3/mt

E. 6 m3/mt

2193. Which is false statement about advantages of multistage compressor in comparison to single stage compressor_________________?
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A. less power requirement

B. less loss of air due to leakage past the cylinder

C. better mechanical balance

D. more effective lubrication

E. lower volumetric efficiency
2194. For minimum work in multistage compression, assuming same index of compression in all stages_________________?
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A. work done in first stage should be more

B. work done in subsequent stages should decrease

C. work done in any stage is no criterion for minimum work but depends on other factors

D. work done in all stages should be equal

E. work done in subsequent stages should increase

2195. A rocket works with maximum overall efficiency when air craft velocity is equal to the_________________?
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A. no such co-relationship with jet velocity exists

B. jet velocity

C. average of the jet velocity

D. twice the jet velocity

E. half the jet velocity
2196. Isothermal compression though most efficient, but is not -practicable because_________________?
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A. it does not increase pressure much

B. it requires cylinder to be placed in water

C. it is impossible in practice

D. ityrequires very big cylinder

E. compressor has to run at very slow speed to achieve it
2197. Pick up the wrong statement ?
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A. ramjet-engine has no turbine

B. bypass turbo-jet engine increases the thrust without adversely affecting, the propulsive efficiency and fuel economy

C. pulsojet requires no ambient air for propulsion

D. propeller is an indirect reaction device

E. turbine drives compressor in a burbojet

2198. Intercooling in gas turbine results in ____________________ ?
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A. increase in net output but decrease in thermal efficiency

B. increase in thermal efficiency but decrease in net output

C. increase in both thermal efficiency and net output

D. decrease in both thermal efficiency and net output

E. none of the above

2199. Volumetric efficiency is_____________________?
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A. the ratio of stroke volume to clearance volume

B. reciprocal of compression ratio

C. proportional to compression ratio

D. the ratio of the air actually delivered to the amount of piston displacement

E. index of compressor performance

2200. Choose the correct statement ________________?
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A. gas turbine requires lot of cooling water

B. gas turbines can be used to generate power only

C. gas turbines have high standby losses and require lot of maintenance

D. gas turbines have flat efficiency at part loads

E. gas turbine is capable of rapid start up and loading